The present invention relates to a latch mechanism. The latch mechanism is primarily, but not exclusively, intended for use on a door of a motor vehicle.
It is known for a motor vehicle latch mechanism to have on a latch bolt thereof, incorporated into an over-mold, a first low energy buffer and a second low energy buffer. Such low energy buffers lower the noise of operation of the latch mechanism. In particular, the first low energy buffer can absorb some of the impact between the latch bolt and an open latch abutment as the latch bolt moves under a spring bias into its open condition. When a latch bolt moves into a closed condition, in which the latch bolt retains a striker mounted on the door frame of the motor vehicle, a pawl moves past a first safety abutment of the latch bolt and is spring biased to engage the latch bolt at a closed abutment to maintain its closed condition. The second low energy buffer can absorb some of the impact between the pawl and that portion of the latch bolt between the first safety abutment and the closed abutment as the pawl, under its spring bias, moves to engage the closed abutment.
When a motor vehicle door is closed, the striker on the door frame engages the latch mechanism. The force of closing the door gives rise to over-travel of the door and hence the latch beyond the closed position.
To absorb, and limit to an extent, over-travel, it is known to provide a separate buffer, mounted on a chassis of the latch mechanism in the line of movement of the closing latch bolt. Such a high energy buffer is designed to absorb much higher impact than the first and second low energy buffers of the latch bolt. Due to its large size and other requirements its has been considered necessary to mount the high energy buffer separately on the chassis at additional cost and assembly time.
An aim of the invention is to provide a latch mechanism having a simplified over-travel buffer arrangement.
Thus according to the present invention there is provided a latch mechanism suitable for a vehicle, the latch mechanism comprising a chassis, and a latch bolt, the latch bolt being movably mounted on the chassis, the latch bolt having an over-mold thereon, the overmold defining a buffer, the chassis also comprising an abutment for the buffer, the latch bolt being moveable between an open position in which it can receive a striker of a vehicle, a closed position in which the striker is capable of being retained by the latch bolt, and an over-travel position in which the striker is in an over-travel position relative to the latch chassis, wherein the buffer is adapted to co-operate with the abutment to absorb over-travel of the latch bolt.
In that way, there is no need for a separate over-travel buffer on the chassis and the cost and assembly time associated with it. Should the latch bolt also require low energy buffers the overmold can be molded to incorporate all the different types of buffers. That is preferable to having a combination of buffers on the chassis and buffers on the latch bolt.
The applicant is the first to realize that it is possible to provide a single overmolding on a latch bolt that is capable of absorbing high energy associated with over-travel of the associated door and also low energy impacts associated with various relatively moving components of the latch mechanism.
These and other features of the present invention will be best understood from the following specification and drawings.